Four human forms in digestive system [salivary and pancreatic α-amylases (endohydrolase); α-maltotriose (oligoglucans); α-maltase-glucoamylase and α-sucrose-isomaltase (exohydrolases)]  Essential for digestion of starch to glucose  Facilitates glucose absorption especially by enterocytes  Involved in metabolic disorders such as type 2 diabetes and obesity due to hyperglycemia  Application for anti-diabetic agents. The gene discussed is MGAM; the disease is Obesity.